As the days lengthen and temperatures rise, gardeners are beginning to venture outdoors to tend the pots and beds that have sat neglected throughout the winter. But before sowing their carrot and kale seeds, many city-dwelling green thumbs may wonder whether the food they will harvest from their urban plots is truly safe to eat.

Soil Kitchen, to be held from noon to 5 p.m. on March 16 and 17 in University City’s Clark Park, will help gardeners determine if their soil is risk-free. The outreach event, organized by Jane Willenbring, an assistant professor in the Department of Earth and Environmental Science at Penn, will provide free soil testing and expert advice.

Participants who bring in a soil sample will receive information about their yard’s lead, arsenic, and cadmium levels. All three types of metals can be toxic to people who handle or breathe in contaminated soil, as well as those who consume fruits and vegetables grown in contaminated plots.

Lead exposure, for example, is known to cause to brain and nervous system damage and lower IQ in young children. Adults are also vulnerable to high lead levels and may experience cognitive declines, muscle pain, and reproductive problems. Lead contamination is widespread in certain areas of Philadelphia, where older homes have leached lead paint into the surrounding yards.

This is the second year Willenbring has presented the Soil Kitchen, an idea she borrowed from an event held during the 2011 National Brownfields Conference in Philadelphia. At last year’s event, held at the John Heinz National Wildlife Refuge, researchers and volunteers tested more than 200 soil samples; this year, Willenbring hopes to increase that number.

A portable X-ray fluorescence instrument will be used to assess whether the metal content of the soil is high or low. Other tests will provide information on the soil texture and pH.

“If we find that people have soil lead, the next obvious question is, ‘What am I supposed to do about that and how is this going to affect me and my children?’” says Willenbring.

Experts will be on hand to offer guidance on techniques to remediate residents’ gardens, such as using raised beds and other techniques to avoid contact with contaminated soils.

For more information about the Soil Kitchen, including instructions on how to collect a soil sample, visit Willenbring’s website.

In case of rain or snow, Soil Kitchen will be held in the lobby of Penn’s Hill College House.